1. Field of the Invention
This invention relates to a cut pile tufting machine and is more particularly concerned with a knife holder assembly for a cut pile tufting machine.
2. Background of the Invention
In the past, cut pile tufting machines have been extensively used for producing fabric, having tufts which are cut at their outer extremities. Such prior art machines usually contain knives in groups of four which are carried by knife blocks. These knife blocks are mounted in succession on a knife bar bracket which is rocked back and forth by a knife drive shaft. Each knife block consists of inner and outer portions within which are formed opposed pairs of channel-shaped slots, the slots receiving the edges of knife blades so as to mount the knives in space parallel relationship. Set screws lock the knives in place. The inner and outer portions of the knife block are joined by a central web, which can be bent, in the event that the set screws on one side of the web are tightened to a greater extent than the set screws on the other side of the web. The inner portion of the knife block is provided with a stub shaft which protudes outwardly therefrom so as to be received in a cylindrical hole in the bracket, there being provided a set screw which locks the cylindrical mounting shaft in place. When this set screw becomes loose or the mounting shaft becomes scored, there is a tendency of the knife block to rotate and thereby loosen the tension which is applied by the upper edge portion of the knives against their respective loopers. This may cause the loops of yarn sewn by the tufting machine to hang up on the loopers.